Code

Build a more generic/powerful query API which writes to a store-writer.
[sysdb.git] / src / core / plugin.c
index bf0bdb34a20af428c73ab63250c7b0f4d3f4c00b..3611be4966b51d296557620e9ed77abda9d7ce48 100644 (file)
@@ -80,31 +80,39 @@ typedef struct {
        void *cb_callback;
        sdb_object_t *cb_user_data;
        ctx_t *cb_ctx;
-} sdb_plugin_cb_t;
-#define SDB_PLUGIN_CB_INIT { SDB_OBJECT_INIT, \
+} callback_t;
+#define CB_INIT { SDB_OBJECT_INIT, \
        /* callback = */ NULL, /* user_data = */ NULL, \
        SDB_PLUGIN_CTX_INIT }
-#define SDB_PLUGIN_CB(obj) ((sdb_plugin_cb_t *)(obj))
-#define SDB_CONST_PLUGIN_CB(obj) ((const sdb_plugin_cb_t *)(obj))
+#define CB(obj) ((callback_t *)(obj))
+#define CONST_CB(obj) ((const callback_t *)(obj))
 
 typedef struct {
-       sdb_plugin_cb_t super;
+       callback_t super;
 #define ccb_callback super.cb_callback
 #define ccb_user_data super.cb_user_data
 #define ccb_ctx super.cb_ctx
        sdb_time_t ccb_interval;
        sdb_time_t ccb_next_update;
-} sdb_plugin_collector_cb_t;
-#define SDB_PLUGIN_CCB(obj) ((sdb_plugin_collector_cb_t *)(obj))
-#define SDB_CONST_PLUGIN_CCB(obj) ((const sdb_plugin_collector_cb_t *)(obj))
+} collector_t;
+#define CCB(obj) ((collector_t *)(obj))
+#define CONST_CCB(obj) ((const collector_t *)(obj))
 
 typedef struct {
-       sdb_plugin_cb_t super; /* cb_callback will always be NULL */
+       callback_t super; /* cb_callback will always be NULL */
 #define w_user_data super.cb_user_data
 #define w_ctx super.cb_ctx
        sdb_store_writer_t impl;
-} sdb_plugin_writer_t;
-#define SDB_PLUGIN_WRITER(obj) ((sdb_plugin_writer_t *)(obj))
+} writer_t;
+#define WRITER(obj) ((writer_t *)(obj))
+
+typedef struct {
+       callback_t super; /* cb_callback will always be NULL */
+#define r_user_data super.cb_user_data
+#define r_ctx super.cb_ctx
+       sdb_store_reader_t impl;
+} reader_t;
+#define READER(obj) ((reader_t *)(obj))
 
 /*
  * private variables
@@ -127,6 +135,7 @@ static sdb_llist_t      *shutdown_list = NULL;
 static sdb_llist_t      *log_list = NULL;
 static sdb_llist_t      *ts_fetcher_list = NULL;
 static sdb_llist_t      *writer_list = NULL;
+static sdb_llist_t      *reader_list = NULL;
 
 static struct {
        const char   *type;
@@ -140,6 +149,7 @@ static struct {
        { "log",                &log_list },
        { "timeseries fetcher", &ts_fetcher_list },
        { "store writer",       &writer_list },
+       { "store reader",       &reader_list },
 };
 
 /*
@@ -181,10 +191,8 @@ ctx_key_init(void)
 static int
 plugin_cmp_next_update(const sdb_object_t *a, const sdb_object_t *b)
 {
-       const sdb_plugin_collector_cb_t *ccb1
-               = (const sdb_plugin_collector_cb_t *)a;
-       const sdb_plugin_collector_cb_t *ccb2
-               = (const sdb_plugin_collector_cb_t *)b;
+       const collector_t *ccb1 = (const collector_t *)a;
+       const collector_t *ccb2 = (const collector_t *)b;
 
        assert(ccb1 && ccb2);
 
@@ -196,7 +204,7 @@ plugin_cmp_next_update(const sdb_object_t *a, const sdb_object_t *b)
 static int
 plugin_lookup_by_name(const sdb_object_t *obj, const void *id)
 {
-       const sdb_plugin_cb_t *cb = SDB_CONST_PLUGIN_CB(obj);
+       const callback_t *cb = CONST_CB(obj);
        const char *name = id;
 
        assert(cb && id);
@@ -225,9 +233,9 @@ plugin_unregister_by_name(const char *plugin_name)
                sdb_llist_t *list = *all_lists[i].list;
 
                while (1) {
-                       sdb_plugin_cb_t *cb;
+                       callback_t *cb;
 
-                       cb = SDB_PLUGIN_CB(sdb_llist_remove(list,
+                       cb = CB(sdb_llist_remove(list,
                                                plugin_lookup_by_name, plugin_name));
                        if (! cb)
                                break;
@@ -358,12 +366,12 @@ plugin_cb_init(sdb_object_t *obj, va_list ap)
 
        /* cb_ctx may be NULL if the plugin was not registered by a plugin */
 
-       SDB_PLUGIN_CB(obj)->cb_callback = callback;
-       SDB_PLUGIN_CB(obj)->cb_ctx      = ctx_get();
-       sdb_object_ref(SDB_OBJ(SDB_PLUGIN_CB(obj)->cb_ctx));
+       CB(obj)->cb_callback = callback;
+       CB(obj)->cb_ctx      = ctx_get();
+       sdb_object_ref(SDB_OBJ(CB(obj)->cb_ctx));
 
        sdb_object_ref(ud);
-       SDB_PLUGIN_CB(obj)->cb_user_data = ud;
+       CB(obj)->cb_user_data = ud;
        return 0;
 } /* plugin_cb_init */
 
@@ -371,19 +379,19 @@ static void
 plugin_cb_destroy(sdb_object_t *obj)
 {
        assert(obj);
-       sdb_object_deref(SDB_PLUGIN_CB(obj)->cb_user_data);
-       sdb_object_deref(SDB_OBJ(SDB_PLUGIN_CB(obj)->cb_ctx));
+       sdb_object_deref(CB(obj)->cb_user_data);
+       sdb_object_deref(SDB_OBJ(CB(obj)->cb_ctx));
 } /* plugin_cb_destroy */
 
-static sdb_type_t sdb_plugin_cb_type = {
-       sizeof(sdb_plugin_cb_t),
+static sdb_type_t callback_type = {
+       sizeof(callback_t),
 
        plugin_cb_init,
        plugin_cb_destroy
 };
 
-static sdb_type_t sdb_plugin_collector_cb_type = {
-       sizeof(sdb_plugin_collector_cb_t),
+static sdb_type_t collector_type = {
+       sizeof(collector_t),
 
        plugin_cb_init,
        plugin_cb_destroy
@@ -398,8 +406,7 @@ plugin_writer_init(sdb_object_t *obj, va_list ap)
        assert(impl);
 
        if ((! impl->store_host) || (! impl->store_service)
-                       || (! impl->store_metric) || (! impl->store_attribute)
-                       || (! impl->store_service_attr) || (! impl->store_metric_attr)) {
+                       || (! impl->store_metric) || (! impl->store_attribute)) {
                sdb_log(SDB_LOG_ERR, "core: store writer callback '%s' "
                                "does not fully implement the writer interface.",
                                obj->name);
@@ -412,14 +419,14 @@ plugin_writer_init(sdb_object_t *obj, va_list ap)
                return -1;
        }
 
-       /* ctx may be NULL if the plugin was not registered by a plugin */
+       /* ctx may be NULL if the callback was not registered by a plugin */
 
-       SDB_PLUGIN_WRITER(obj)->impl = *impl;
-       SDB_PLUGIN_WRITER(obj)->w_ctx  = ctx_get();
-       sdb_object_ref(SDB_OBJ(SDB_PLUGIN_WRITER(obj)->w_ctx));
+       WRITER(obj)->impl = *impl;
+       WRITER(obj)->w_ctx  = ctx_get();
+       sdb_object_ref(SDB_OBJ(WRITER(obj)->w_ctx));
 
        sdb_object_ref(ud);
-       SDB_PLUGIN_WRITER(obj)->w_user_data = ud;
+       WRITER(obj)->w_user_data = ud;
        return 0;
 } /* plugin_writer_init */
 
@@ -427,17 +434,64 @@ static void
 plugin_writer_destroy(sdb_object_t *obj)
 {
        assert(obj);
-       sdb_object_deref(SDB_PLUGIN_WRITER(obj)->w_user_data);
-       sdb_object_deref(SDB_OBJ(SDB_PLUGIN_WRITER(obj)->w_ctx));
+       sdb_object_deref(WRITER(obj)->w_user_data);
+       sdb_object_deref(SDB_OBJ(WRITER(obj)->w_ctx));
 } /* plugin_writer_destroy */
 
-static sdb_type_t sdb_plugin_writer_type = {
-       sizeof(sdb_plugin_writer_t),
+static sdb_type_t writer_type = {
+       sizeof(writer_t),
 
        plugin_writer_init,
        plugin_writer_destroy
 };
 
+static int
+plugin_reader_init(sdb_object_t *obj, va_list ap)
+{
+       sdb_store_reader_t *impl = va_arg(ap, sdb_store_reader_t *);
+       sdb_object_t       *ud   = va_arg(ap, sdb_object_t *);
+
+       assert(impl);
+
+       if ((! impl->prepare_query) || (! impl->execute_query)) {
+               sdb_log(SDB_LOG_ERR, "core: store reader callback '%s' "
+                               "does not fully implement the reader interface.",
+                               obj->name);
+               return -1;
+       }
+       if (sdb_llist_search_by_name(reader_list, obj->name)) {
+               sdb_log(SDB_LOG_WARNING, "core: store reader callback '%s' "
+                               "has already been registered. Ignoring newly "
+                               "registered version.", obj->name);
+               return -1;
+       }
+
+       /* ctx may be NULL if the callback was not registered by a plugin */
+
+       READER(obj)->impl = *impl;
+       READER(obj)->r_ctx  = ctx_get();
+       sdb_object_ref(SDB_OBJ(READER(obj)->r_ctx));
+
+       sdb_object_ref(ud);
+       READER(obj)->r_user_data = ud;
+       return 0;
+} /* plugin_reader_init */
+
+static void
+plugin_reader_destroy(sdb_object_t *obj)
+{
+       assert(obj);
+       sdb_object_deref(READER(obj)->r_user_data);
+       sdb_object_deref(SDB_OBJ(READER(obj)->r_ctx));
+} /* plugin_reader_destroy */
+
+static sdb_type_t reader_type = {
+       sizeof(reader_t),
+
+       plugin_reader_init,
+       plugin_reader_destroy
+};
+
 static int
 module_init(const char *name, lt_dlhandle lh, sdb_plugin_info_t *info)
 {
@@ -589,7 +643,7 @@ plugin_add_callback(sdb_llist_t **list, const char *type,
        if (! *list)
                return -1;
 
-       obj = sdb_object_create(name, sdb_plugin_cb_type,
+       obj = sdb_object_create(name, callback_type,
                        list, type, callback, user_data);
        if (! obj)
                return -1;
@@ -607,6 +661,21 @@ plugin_add_callback(sdb_llist_t **list, const char *type,
        return 0;
 } /* plugin_add_callback */
 
+static void
+get_backend(char **backends, size_t *backends_num)
+{
+       const sdb_plugin_info_t *info;
+
+       info = sdb_plugin_current();
+       if ((! info) || (! info->plugin_name) || (! *info->plugin_name)) {
+               *backends_num = 0;
+               return;
+       }
+
+       backends[0] = info->plugin_name;
+       *backends_num = 1;
+} /* get_backend */
+
 /*
  * public API
  */
@@ -783,13 +852,13 @@ sdb_plugin_register_collector(const char *name, sdb_plugin_collector_cb callback
 
        plugin_get_name(name, cb_name, sizeof(cb_name));
 
-       obj = sdb_object_create(cb_name, sdb_plugin_collector_cb_type,
+       obj = sdb_object_create(cb_name, collector_type,
                        &collector_list, "collector", callback, user_data);
        if (! obj)
                return -1;
 
        if (interval)
-               SDB_PLUGIN_CCB(obj)->ccb_interval = *interval;
+               CCB(obj)->ccb_interval = *interval;
        else {
                ctx_t *ctx = ctx_get();
 
@@ -800,10 +869,10 @@ sdb_plugin_register_collector(const char *name, sdb_plugin_collector_cb callback
                        return -1;
                }
 
-               SDB_PLUGIN_CCB(obj)->ccb_interval = ctx->public.interval;
+               CCB(obj)->ccb_interval = ctx->public.interval;
        }
 
-       if (! (SDB_PLUGIN_CCB(obj)->ccb_next_update = sdb_gettime())) {
+       if (! (CCB(obj)->ccb_next_update = sdb_gettime())) {
                char errbuf[1024];
                sdb_log(SDB_LOG_ERR, "core: Failed to determine current "
                                "time: %s", sdb_strerror(errno, errbuf, sizeof(errbuf)));
@@ -822,7 +891,7 @@ sdb_plugin_register_collector(const char *name, sdb_plugin_collector_cb callback
 
        sdb_log(SDB_LOG_INFO, "core: Registered collector callback '%s' "
                        "(interval = %.3fs).", cb_name,
-                       SDB_TIME_TO_DOUBLE(SDB_PLUGIN_CCB(obj)->ccb_interval));
+                       SDB_TIME_TO_DOUBLE(CCB(obj)->ccb_interval));
        return 0;
 } /* sdb_plugin_register_collector */
 
@@ -851,7 +920,7 @@ sdb_plugin_register_writer(const char *name,
 
        plugin_get_name(name, cb_name, sizeof(cb_name));
 
-       obj = sdb_object_create(cb_name, sdb_plugin_writer_type,
+       obj = sdb_object_create(cb_name, writer_type,
                        writer, user_data);
        if (! obj)
                return -1;
@@ -869,6 +938,41 @@ sdb_plugin_register_writer(const char *name,
        return 0;
 } /* sdb_store_register_writer */
 
+int
+sdb_plugin_register_reader(const char *name,
+               sdb_store_reader_t *reader, sdb_object_t *user_data)
+{
+       char cb_name[1024];
+       sdb_object_t *obj;
+
+       if ((! name) || (! reader))
+               return -1;
+
+       if (! reader_list)
+               reader_list = sdb_llist_create();
+       if (! reader_list)
+               return -1;
+
+       plugin_get_name(name, cb_name, sizeof(cb_name));
+
+       obj = sdb_object_create(cb_name, reader_type,
+                       reader, user_data);
+       if (! obj)
+               return -1;
+
+       if (sdb_llist_append(reader_list, obj)) {
+               sdb_object_deref(obj);
+               return -1;
+       }
+
+       /* pass control to the list */
+       sdb_object_deref(obj);
+
+       sdb_log(SDB_LOG_INFO, "core: Registered store reader callback '%s'.",
+                       cb_name);
+       return 0;
+} /* sdb_plugin_register_reader */
+
 void
 sdb_plugin_unregister_all(void)
 {
@@ -934,7 +1038,7 @@ sdb_plugin_current(void)
 int
 sdb_plugin_configure(const char *name, oconfig_item_t *ci)
 {
-       sdb_plugin_cb_t *plugin;
+       callback_t *plugin;
        sdb_plugin_config_cb callback;
 
        ctx_t *old_ctx;
@@ -944,7 +1048,7 @@ sdb_plugin_configure(const char *name, oconfig_item_t *ci)
        if ((! name) || (! ci))
                return -1;
 
-       plugin = SDB_PLUGIN_CB(sdb_llist_search_by_name(config_list, name));
+       plugin = CB(sdb_llist_search_by_name(config_list, name));
        if (! plugin) {
                ctx_t *ctx = CTX(sdb_llist_search_by_name(all_plugins, name));
                if (! ctx)
@@ -976,11 +1080,11 @@ sdb_plugin_reconfigure_init(void)
 
        /* deconfigure all plugins */
        while (sdb_llist_iter_has_next(iter)) {
-               sdb_plugin_cb_t *plugin;
+               callback_t *plugin;
                sdb_plugin_config_cb callback;
                ctx_t *old_ctx;
 
-               plugin = SDB_PLUGIN_CB(sdb_llist_iter_get_next(iter));
+               plugin = CB(sdb_llist_iter_get_next(iter));
                old_ctx = ctx_set(plugin->cb_ctx);
                callback = (sdb_plugin_config_cb)plugin->cb_callback;
                callback(NULL);
@@ -1033,13 +1137,13 @@ sdb_plugin_init_all(void)
 
        iter = sdb_llist_get_iter(init_list);
        while (sdb_llist_iter_has_next(iter)) {
-               sdb_plugin_cb_t *cb;
+               callback_t *cb;
                sdb_plugin_init_cb callback;
                ctx_t *old_ctx;
 
                sdb_object_t *obj = sdb_llist_iter_get_next(iter);
                assert(obj);
-               cb = SDB_PLUGIN_CB(obj);
+               cb = CB(obj);
 
                callback = (sdb_plugin_init_cb)cb->cb_callback;
 
@@ -1066,13 +1170,13 @@ sdb_plugin_shutdown_all(void)
 
        iter = sdb_llist_get_iter(shutdown_list);
        while (sdb_llist_iter_has_next(iter)) {
-               sdb_plugin_cb_t *cb;
+               callback_t *cb;
                sdb_plugin_shutdown_cb callback;
                ctx_t *old_ctx;
 
                sdb_object_t *obj = sdb_llist_iter_get_next(iter);
                assert(obj);
-               cb = SDB_PLUGIN_CB(obj);
+               cb = CB(obj);
 
                callback = (sdb_plugin_shutdown_cb)cb->cb_callback;
 
@@ -1110,18 +1214,18 @@ sdb_plugin_collector_loop(sdb_plugin_loop_t *loop)
                if (! obj)
                        return -1;
 
-               callback = (sdb_plugin_collector_cb)SDB_PLUGIN_CCB(obj)->ccb_callback;
+               callback = (sdb_plugin_collector_cb)CCB(obj)->ccb_callback;
 
                if (! (now = sdb_gettime())) {
                        char errbuf[1024];
                        sdb_log(SDB_LOG_ERR, "core: Failed to determine current "
                                        "time in collector main loop: %s",
                                        sdb_strerror(errno, errbuf, sizeof(errbuf)));
-                       now = SDB_PLUGIN_CCB(obj)->ccb_next_update;
+                       now = CCB(obj)->ccb_next_update;
                }
 
-               if (now < SDB_PLUGIN_CCB(obj)->ccb_next_update) {
-                       interval = SDB_PLUGIN_CCB(obj)->ccb_next_update - now;
+               if (now < CCB(obj)->ccb_next_update) {
+                       interval = CCB(obj)->ccb_next_update - now;
 
                        errno = 0;
                        while (loop->do_loop && sdb_sleep(interval, &interval)) {
@@ -1147,13 +1251,13 @@ sdb_plugin_collector_loop(sdb_plugin_loop_t *loop)
                        }
                }
 
-               old_ctx = ctx_set(SDB_PLUGIN_CCB(obj)->ccb_ctx);
-               if (callback(SDB_PLUGIN_CCB(obj)->ccb_user_data)) {
+               old_ctx = ctx_set(CCB(obj)->ccb_ctx);
+               if (callback(CCB(obj)->ccb_user_data)) {
                        /* XXX */
                }
                ctx_set(old_ctx);
 
-               interval = SDB_PLUGIN_CCB(obj)->ccb_interval;
+               interval = CCB(obj)->ccb_interval;
                if (! interval)
                        interval = loop->default_interval;
                if (! interval) {
@@ -1164,21 +1268,21 @@ sdb_plugin_collector_loop(sdb_plugin_loop_t *loop)
                        continue;
                }
 
-               SDB_PLUGIN_CCB(obj)->ccb_next_update += interval;
+               CCB(obj)->ccb_next_update += interval;
 
                if (! (now = sdb_gettime())) {
                        char errbuf[1024];
                        sdb_log(SDB_LOG_ERR, "core: Failed to determine current "
                                        "time in collector main loop: %s",
                                        sdb_strerror(errno, errbuf, sizeof(errbuf)));
-                       now = SDB_PLUGIN_CCB(obj)->ccb_next_update;
+                       now = CCB(obj)->ccb_next_update;
                }
 
-               if (now > SDB_PLUGIN_CCB(obj)->ccb_next_update) {
+               if (now > CCB(obj)->ccb_next_update) {
                        sdb_log(SDB_LOG_WARNING, "core: Plugin '%s' took too "
                                        "long; skipping iterations to keep up.",
                                        obj->name);
-                       SDB_PLUGIN_CCB(obj)->ccb_next_update = now;
+                       CCB(obj)->ccb_next_update = now;
                }
 
                if (sdb_llist_insert_sorted(collector_list, obj,
@@ -1216,8 +1320,8 @@ sdb_plugin_cname(char *hostname)
                sdb_object_t *obj = sdb_llist_iter_get_next(iter);
                assert(obj);
 
-               callback = (sdb_plugin_cname_cb)SDB_PLUGIN_CB(obj)->cb_callback;
-               cname = callback(hostname, SDB_PLUGIN_CB(obj)->cb_user_data);
+               callback = (sdb_plugin_cname_cb)CB(obj)->cb_callback;
+               cname = callback(hostname, CB(obj)->cb_user_data);
                if (cname) {
                        free(hostname);
                        hostname = cname;
@@ -1247,12 +1351,12 @@ sdb_plugin_log(int prio, const char *msg)
                sdb_object_t *obj = sdb_llist_iter_get_next(iter);
                assert(obj);
 
-               callback = (sdb_plugin_log_cb)SDB_PLUGIN_CB(obj)->cb_callback;
-               tmp = callback(prio, msg, SDB_PLUGIN_CB(obj)->cb_user_data);
+               callback = (sdb_plugin_log_cb)CB(obj)->cb_callback;
+               tmp = callback(prio, msg, CB(obj)->cb_user_data);
                if (tmp > ret)
                        ret = tmp;
 
-               if (SDB_PLUGIN_CB(obj)->cb_ctx)
+               if (CB(obj)->cb_ctx)
                        logged = 1;
                /* else: this is an internally registered callback */
        }
@@ -1308,7 +1412,7 @@ sdb_timeseries_t *
 sdb_plugin_fetch_timeseries(const char *type, const char *id,
                sdb_timeseries_opts_t *opts)
 {
-       sdb_plugin_cb_t *plugin;
+       callback_t *plugin;
        sdb_plugin_fetch_ts_cb callback;
        sdb_timeseries_t *ts;
 
@@ -1317,7 +1421,7 @@ sdb_plugin_fetch_timeseries(const char *type, const char *id,
        if ((! type) || (! id) || (! opts))
                return NULL;
 
-       plugin = SDB_PLUGIN_CB(sdb_llist_search_by_name(ts_fetcher_list, type));
+       plugin = CB(sdb_llist_search_by_name(ts_fetcher_list, type));
        if (! plugin) {
                sdb_log(SDB_LOG_ERR, "core: Cannot fetch time-series of type %s: "
                                "no such plugin loaded", type);
@@ -1332,24 +1436,93 @@ sdb_plugin_fetch_timeseries(const char *type, const char *id,
        return ts;
 } /* sdb_plugin_fetch_timeseries */
 
+int
+sdb_plugin_query(sdb_ast_node_t *ast,
+               sdb_store_writer_t *w, sdb_object_t *wd, sdb_strbuf_t *errbuf)
+{
+       size_t n = sdb_llist_len(reader_list);
+       reader_t *reader;
+       sdb_object_t *q;
+       int status = 0;
+
+       if (! ast)
+               return 0;
+
+       if ((ast->type != SDB_AST_TYPE_FETCH)
+                       && (ast->type != SDB_AST_TYPE_LIST)
+                       && (ast->type != SDB_AST_TYPE_LOOKUP)) {
+               sdb_log(SDB_LOG_ERR, "core: Cannot execute query of type %s",
+                               SDB_AST_TYPE_TO_STRING(ast));
+               sdb_strbuf_sprintf(errbuf, "Cannot execute query of type %s",
+                               SDB_AST_TYPE_TO_STRING(ast));
+               return -1;
+       }
+
+       if (n != 1) {
+               char *msg = (n > 0)
+                       ? "Cannot execute query: multiple readers not supported"
+                       : "Cannot execute query: no readers registered";
+               sdb_strbuf_sprintf(errbuf, "%s", msg);
+               sdb_log(SDB_LOG_ERR, "core: %s", msg);
+               return -1;
+       }
+
+       reader = READER(sdb_llist_get(reader_list, 0));
+       assert(reader);
+
+       q = reader->impl.prepare_query(ast, errbuf, reader->r_user_data);
+       if (q)
+               status = reader->impl.execute_query(q, w, SDB_OBJ(wd),
+                               errbuf, reader->r_user_data);
+       else
+               status = -1;
+
+       sdb_object_deref(SDB_OBJ(q));
+       sdb_object_deref(SDB_OBJ(reader));
+       return status;
+} /* sdb_plugin_query */
+
 int
 sdb_plugin_store_host(const char *name, sdb_time_t last_update)
 {
+       sdb_store_host_t host = { 0 };
+       char *backends[1];
+       char *cname;
+
        sdb_llist_iter_t *iter;
        int status = 0;
 
        if (! name)
                return -1;
 
+       if (! sdb_llist_len(writer_list)) {
+               sdb_log(SDB_LOG_ERR, "core: Cannot store host: "
+                               "no writers registered");
+               return -1;
+       }
+
+       cname = sdb_plugin_cname(strdup(name));
+       if (! cname) {
+               sdb_log(SDB_LOG_ERR, "core: strdup failed");
+               return -1;
+       }
+
+       host.name = cname;
+       host.last_update = last_update;
+       host.backends = (const char * const *)backends;
+       get_backend(backends, &host.backends_num);
+
        iter = sdb_llist_get_iter(writer_list);
        while (sdb_llist_iter_has_next(iter)) {
-               sdb_plugin_writer_t *writer;
-               writer = SDB_PLUGIN_WRITER(sdb_llist_iter_get_next(iter));
+               writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+               int s;
                assert(writer);
-               if (writer->impl.store_host(name, last_update, writer->w_user_data))
-                       status = -1;
+               s = writer->impl.store_host(&host, writer->w_user_data);
+               if (((s > 0) && (status >= 0)) || (s < 0))
+                       status = s;
        }
        sdb_llist_iter_destroy(iter);
+       free(cname);
        return status;
 } /* sdb_plugin_store_host */
 
@@ -1357,22 +1530,57 @@ int
 sdb_plugin_store_service(const char *hostname, const char *name,
                sdb_time_t last_update)
 {
+       sdb_store_service_t service = { 0 };
+       char *backends[1];
+       char *cname;
+
        sdb_llist_iter_t *iter;
+       sdb_data_t d;
+
        int status = 0;
 
        if ((! hostname) || (! name))
                return -1;
 
+       if (! sdb_llist_len(writer_list)) {
+               sdb_log(SDB_LOG_ERR, "core: Cannot store service: "
+                               "no writers registered");
+               return -1;
+       }
+
+       cname = sdb_plugin_cname(strdup(hostname));
+       if (! cname) {
+               sdb_log(SDB_LOG_ERR, "core: strdup failed");
+               return -1;
+       }
+
+       service.hostname = cname;
+       service.name = name;
+       service.last_update = last_update;
+       service.backends = (const char * const *)backends;
+       get_backend(backends, &service.backends_num);
+
        iter = sdb_llist_get_iter(writer_list);
        while (sdb_llist_iter_has_next(iter)) {
-               sdb_plugin_writer_t *writer;
-               writer = SDB_PLUGIN_WRITER(sdb_llist_iter_get_next(iter));
+               writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+               int s;
                assert(writer);
-               if (writer->impl.store_service(hostname, name, last_update,
-                                       writer->w_user_data))
-                       status = -1;
+               s = writer->impl.store_service(&service, writer->w_user_data);
+               if (((s > 0) && (status >= 0)) || (s < 0))
+                       status = s;
        }
        sdb_llist_iter_destroy(iter);
+
+       if (! status) {
+               /* record the hostname as an attribute */
+               d.type = SDB_TYPE_STRING;
+               d.data.string = cname;
+               if (sdb_plugin_store_service_attribute(cname, name,
+                                       "hostname", &d, last_update))
+                       status = -1;
+       }
+
+       free(cname);
        return status;
 } /* sdb_plugin_store_service */
 
@@ -1380,25 +1588,64 @@ int
 sdb_plugin_store_metric(const char *hostname, const char *name,
                sdb_metric_store_t *store, sdb_time_t last_update)
 {
+       sdb_store_metric_t metric = { 0 };
+       char *backends[1];
+       char *cname;
+
        sdb_llist_iter_t *iter;
+       sdb_data_t d;
+
        int status = 0;
 
        if ((! hostname) || (! name))
                return -1;
 
-       if ((! store->type) || (! store->id))
+       if (! sdb_llist_len(writer_list)) {
+               sdb_log(SDB_LOG_ERR, "core: Cannot store metric: "
+                               "no writers registered");
+               return -1;
+       }
+
+       cname = sdb_plugin_cname(strdup(hostname));
+       if (! cname) {
+               sdb_log(SDB_LOG_ERR, "core: strdup failed");
+               return -1;
+       }
+
+       if (store && ((! store->type) || (! store->id)))
                store = NULL;
 
+       metric.hostname = cname;
+       metric.name = name;
+       if (store) {
+               metric.store.type = store->type;
+               metric.store.id = store->id;
+       }
+       metric.last_update = last_update;
+       metric.backends = (const char * const *)backends;
+       get_backend(backends, &metric.backends_num);
+
        iter = sdb_llist_get_iter(writer_list);
        while (sdb_llist_iter_has_next(iter)) {
-               sdb_plugin_writer_t *writer;
-               writer = SDB_PLUGIN_WRITER(sdb_llist_iter_get_next(iter));
+               writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+               int s;
                assert(writer);
-               if (writer->impl.store_metric(hostname, name, store, last_update,
-                                       writer->w_user_data))
-                       status = -1;
+               s = writer->impl.store_metric(&metric, writer->w_user_data);
+               if (((s > 0) && (status >= 0)) || (s < 0))
+                       status = s;
        }
        sdb_llist_iter_destroy(iter);
+
+       if (! status) {
+               /* record the hostname as an attribute */
+               d.type = SDB_TYPE_STRING;
+               d.data.string = cname;
+               if (sdb_plugin_store_metric_attribute(cname, name,
+                                       "hostname", &d, last_update))
+                       status = -1;
+       }
+
+       free(cname);
        return status;
 } /* sdb_plugin_store_metric */
 
@@ -1406,22 +1653,47 @@ int
 sdb_plugin_store_attribute(const char *hostname, const char *key,
                const sdb_data_t *value, sdb_time_t last_update)
 {
+       sdb_store_attribute_t attr = { 0 };
+       char *backends[1];
+       char *cname;
+
        sdb_llist_iter_t *iter;
        int status = 0;
 
        if ((! hostname) || (! key) || (! value))
                return -1;
 
+       if (! sdb_llist_len(writer_list)) {
+               sdb_log(SDB_LOG_ERR, "core: Cannot store attribute: "
+                               "no writers registered");
+               return -1;
+       }
+
+       cname = sdb_plugin_cname(strdup(hostname));
+       if (! cname) {
+               sdb_log(SDB_LOG_ERR, "core: strdup failed");
+               return -1;
+       }
+
+       attr.parent_type = SDB_HOST;
+       attr.parent = cname;
+       attr.key = key;
+       attr.value = *value;
+       attr.last_update = last_update;
+       attr.backends = (const char * const *)backends;
+       get_backend(backends, &attr.backends_num);
+
        iter = sdb_llist_get_iter(writer_list);
        while (sdb_llist_iter_has_next(iter)) {
-               sdb_plugin_writer_t *writer;
-               writer = SDB_PLUGIN_WRITER(sdb_llist_iter_get_next(iter));
+               writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+               int s;
                assert(writer);
-               if (writer->impl.store_attribute(hostname, key, value, last_update,
-                                       writer->w_user_data))
-                       status = -1;
+               s = writer->impl.store_attribute(&attr, writer->w_user_data);
+               if (((s > 0) && (status >= 0)) || (s < 0))
+                       status = s;
        }
        sdb_llist_iter_destroy(iter);
+       free(cname);
        return status;
 } /* sdb_plugin_store_attribute */
 
@@ -1429,22 +1701,48 @@ int
 sdb_plugin_store_service_attribute(const char *hostname, const char *service,
                const char *key, const sdb_data_t *value, sdb_time_t last_update)
 {
+       sdb_store_attribute_t attr = { 0 };
+       char *backends[1];
+       char *cname;
+
        sdb_llist_iter_t *iter;
        int status = 0;
 
        if ((! hostname) || (! service) || (! key) || (! value))
                return -1;
 
+       if (! sdb_llist_len(writer_list)) {
+               sdb_log(SDB_LOG_ERR, "core: Cannot store service attribute: "
+                               "no writers registered");
+               return -1;
+       }
+
+       cname = sdb_plugin_cname(strdup(hostname));
+       if (! cname) {
+               sdb_log(SDB_LOG_ERR, "core: strdup failed");
+               return -1;
+       }
+
+       attr.hostname = cname;
+       attr.parent_type = SDB_SERVICE;
+       attr.parent = service;
+       attr.key = key;
+       attr.value = *value;
+       attr.last_update = last_update;
+       attr.backends = (const char * const *)backends;
+       get_backend(backends, &attr.backends_num);
+
        iter = sdb_llist_get_iter(writer_list);
        while (sdb_llist_iter_has_next(iter)) {
-               sdb_plugin_writer_t *writer;
-               writer = SDB_PLUGIN_WRITER(sdb_llist_iter_get_next(iter));
+               writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+               int s;
                assert(writer);
-               if (writer->impl.store_service_attr(hostname, service,
-                                       key, value, last_update, writer->w_user_data))
-                       status = -1;
+               s = writer->impl.store_attribute(&attr, writer->w_user_data);
+               if (((s > 0) && (status >= 0)) || (s < 0))
+                       status = s;
        }
        sdb_llist_iter_destroy(iter);
+       free(cname);
        return status;
 } /* sdb_plugin_store_service_attribute */
 
@@ -1452,22 +1750,48 @@ int
 sdb_plugin_store_metric_attribute(const char *hostname, const char *metric,
                const char *key, const sdb_data_t *value, sdb_time_t last_update)
 {
+       sdb_store_attribute_t attr = { 0 };
+       char *backends[1];
+       char *cname;
+
        sdb_llist_iter_t *iter;
        int status = 0;
 
        if ((! hostname) || (! metric) || (! key) || (! value))
                return -1;
 
+       if (! sdb_llist_len(writer_list)) {
+               sdb_log(SDB_LOG_ERR, "core: Cannot store metric attribute: "
+                               "no writers registered");
+               return -1;
+       }
+
+       cname = sdb_plugin_cname(strdup(hostname));
+       if (! cname) {
+               sdb_log(SDB_LOG_ERR, "core: strdup failed");
+               return -1;
+       }
+
+       attr.hostname = cname;
+       attr.parent_type = SDB_METRIC;
+       attr.parent = metric;
+       attr.key = key;
+       attr.value = *value;
+       attr.last_update = last_update;
+       attr.backends = (const char * const *)backends;
+       get_backend(backends, &attr.backends_num);
+
        iter = sdb_llist_get_iter(writer_list);
        while (sdb_llist_iter_has_next(iter)) {
-               sdb_plugin_writer_t *writer;
-               writer = SDB_PLUGIN_WRITER(sdb_llist_iter_get_next(iter));
+               writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+               int s;
                assert(writer);
-               if (writer->impl.store_metric_attr(hostname, metric,
-                                       key, value, last_update, writer->w_user_data))
-                       status = -1;
+               s = writer->impl.store_attribute(&attr, writer->w_user_data);
+               if (((s > 0) && (status >= 0)) || (s < 0))
+                       status = s;
        }
        sdb_llist_iter_destroy(iter);
+       free(cname);
        return status;
 } /* sdb_plugin_store_metric_attribute */